I got nearly the same problem yesterday evening. I bought an Avatar of Frost (1050 BFP) and a Mountaineer (1250 BFP) directly after each other in the AH. I received the cards by Mail. The cards have been visible in my card library. I could summon them in the Forge once. And after that they are suddenly gone from my library. 3 mins later a System admin released a System massage that the AH is broken somehow.
Now I lost 2,300 BFP and the two cards.
For me it is the first time that something got lost.
Is there any possibility to get the BFP or cards back?